Yarn detecting mechanism for textile machine stop motions



C. S. MARTIN ET AL YARN DETECTING MECHANISM FOR TEXTILE MACHINE STOP MOTIONS Filed Feb. 17. 1953 May 1, 1956 F/GB.

/ A Homey United States Patent O YARN DETECTING MECHANISM FOR TEXTILE MACHINE STOP MOTIONS Charles Stanley Martin and Albert Edward Cooke, Leicester, England, assignors to Trip-Lite Limited, Leicester, England Application February 17, 1953, Serial No. 337,382

7 Claims. (Cl. 200-61.18)

This invention concerns a yarn detecting mechanism for stop motions of knitting machines and other textile machines; a textile machine for the purpose of the present specification is dened as a machine which manipulates a textile yarn or thread or a plurality of textile yarns or threads. An object of the present invention is a detecting mechanism which will not only detect the absence of yarn but will also detect an undue increase and an undue decrease in the tension of the yarn, such detection serving to bring the stop motion into operation. The expression stop motion is employed in this specification in the same broad sense that it is used in the textile trade to include not only a motion (i. e. mechanism or apparatus) whereby the machine is actually brought to rest but also a motion whereby certain operations of the machine are suspended: for example to obviate the ill effects that would otherwise follow the occurrence of that fault which the detector mechanism has detected.

A specific object of the invention is an improved detector mechanism in which the working parts are in the main totally enclosed against the ingress of lint and dust but which is easily threaded up.

The invention provides a yarn detecting mechanism for textile machine stop motions, constructed and arranged to detect the absence of the yarn and undue increase and decrease in yarn tension, and comprising two co-operating yarn-engaging devices viz. a support for supporting yarn against the tension thereof and a feeler for support by the yarn, means mounting the support for yielding movement in the event of undue increase in yarn tension, means mounting the feeler for movement in the same directiton upon absence of yarn and upon undue decrease in yarn tension and upon said yielding movement of the support, and stop motion actuating means (e. g. electrical contacts arranged to be made or broken) operable upon such movement of the feeler. It will be appreciated that if the tension in the yarn increases unduly the pull in the yarn causes the support to yield; the feeler follows this movement and operates the actuating means. lf the yarn tension falls unduly then the yarn will not possess sufficient rigidity to support the feeler and again the latter will move and operate the actuating means. In a similar manner the feeler will move should the yarn break. There may also be further actuating means (additional to that mentioned above) operable upon yielding movement of the support. Such further actuating means may consist of electrical contacts arranged to be made or broken, for example upon momentary increase in yarn tension.

Preferably the support is movable upon undue increase in yarn tension to a yarn discharging position and according to an important subsidiary feature of the invention there is a snap action or over-centre device operable upon a predetermined degree of movement of the support for moving the latter into the discharge position or past that position into an extreme position.

According to an important subsidiary feature of the invention the actuating means and the snap action device 2,744,174 Patented May 1, 1956 ICC are enclosed in a box-like casing from which the support and feeler project. Thus the more delicate parts of the mechanism are protected against the ingress of lint or dust. Moreover, the support is visible and since it moves with a snap action into the discharge position or into the extreme position (as the case may be) upon detection of undue yarn tension, an operator can readily observe which one of a number of the devices (and many textile machines may incorporate a great number thereof) has operated. This visual check is not possible with those existing detecting mechanisms in which the yarn-engaging parts or certain thereof resume their original position after operation. It is a further advantage of the provision of the snap action device that the support is presented for easy re-threading.

The foregoing and other features of the invention set out in the appended claims are incorporated in the mechanism which will now be described as an example with reference to the accompanying drawings in which:

Figure 1 is a perspective view of the mechanism;

Figure 2 is a sectional elevation thereof;

Figure 3 is a rear elevation thereof, with a cover plate removed to disclose parts within the box-like casing.

This mechanism comprises a rectangular box-like metal or synthetic resin casing 1 closed against ingress of fluff but having a removable cover plate 2. Two opposed sides 1a of this casing are pierced with holes in which the journals 3 of a crank 4 contained within the casing are rotatably mounted. The outer end of each journal is attached to an arm 5 and the free ends of these arms 5 are connected by a cross bar 6 so that they are of U-shape. This U-shaped device together with the platform, hereinafter mentioned, constitutes the yarn support 7 and it will be convenient for ease in description to envisage the mechanism in such an attitude that the yarn support 7 extends horizontally and the box is disposed vertically as in the drawings. The horizontal (and operative) position of the support 7 is determined by stops 8 in the box limiting movement of the crank 4. From the cross bar 6 of the U a sheet metal platform 9 extends towards the box in the plane of the arms and then turns at right angles, to protrude substantially vertically upwards as at 10.

Also pivoted in the two opposed sides 1a of the box 1 at a lower level than, and nearer the free end of the support 7 than the journals 3, there is a wire spindle 11 the outer ends of which are attached to a pair of protruding feeler wires 12 (the feeler aforesaid), the outer ends of which are turned downwards as at 13. These feeler wires 12 are arranged to rest on yarn Y which runs over the support 7 as shown in Fig. l, and in this attitude, are disposed each between one arm 5 of the support and the platform 9. The down-turned ends 13 of the feeler wires prevent the yarn from escaping from beneath these wires while the yarn is running normally (during which there are some minor fluctuations in the attitude of these wires and/ or of the support 7), and their length and the angle between them and the wires (desirably about 70) should be adequate for this purpose. A further criterion of the desirable length of these downturned ends 13 is also mentioned later on.

Inside the box 1 the spindle 11 is provided with an upwardly protruding contact finger 14 which, when the feeler wires 12 drop, makes contact with a stationary contact 15 to complete an electrical circuit. These two contacts constitute the stop motion actuating means. The stationary contact 1S is insulated from the box 1; if the latter is metal, and is connected by means 17 to a suitable terminal 16 on the outside of the box (but insulated therefrom if the latter is of metal). If the box is of metal, it constitutes the other terminal of the electric circuit.

lf, as is preferred, thebox 1 is of non-conducting material, a separate terminal is provided. In the illustrated construction the separate terminal is constituted by a spring clip 18 by which the box may be releasably mounted on the frameworkof a .textile machine. This spring clip 1S is connected by screws 1910 a plate 20 inside the box 1. A spring wire 21 engages those screws, and has one end pressing against a lmetal plate 22 which closes a slot 23 in the front of .the box and engages (and forms part of the pivotal mounting of) the spindle 11. Movement of the feeler wires 12 in the contact-separating direction is limited by a stop 24 constituted by a retaining screw for plate 22.

Movement of the support 7 downwards under yarn tension is opposed by a biasing spring. The crank 4 protrudes downwards in the box and has one end of a tension spring 25 attached to it, the other end or which spring is connected to an anchorage 26 in the upper part of the box. This mechanism constitutes a snap action or over-centre device because as the support 7 swings downwards the crank 4 gradually moves against the pull of the spring 25 into a dead centre position in which the direction of the spring pull is aligned with the plane ot' the crank. Immediately the crank 4 passes the dead centre position its further movement is implemented by the spring tension, until the crank arms 5 move against opposed stops 27.

It will be appreciated that the further the support 7 moves from its normal horizontal position towards the dead centre position of the crank the smaller is the opposing force provided by the spring 25. This is an advantage.

The movement of the support 7 past the dead centre position cannot be followed by the feeler 12 (movement of the latter being terminated by ixed contact Therefore the support eventually moves under the spring bias to a position in which it is clear of the down-turned ends of the feeler wires. In this position the yarn running across the support 7 can slide olf the end of the latter.

The length or" the down-turned ends 13 of the feeler should be such that, when the feeler reaches its lowest position (determined by engagement of iinger 14 with contact 15), they extend beyond the dead centre position of the support 7 so that the yarn cannot slip oit the support 7 until the latter passes its dead centre position.

The spring bias applied to the support 7 is adjustable. For this purpose the top end of the tension spring is connected by a exible cord 28 (e. g. of nylon) to a spindle 26 journalled in the upper part of the box so that by rotating the spindle the cord may be wound on to or off it. At the outside of the box the spindle 26 is provided with a knurled or uted knob 29 by which it may be rotated and with a spring Iinger or detent 30 which engages the lperiphery of the knob to prevent accidental rotation Yof the latter. This detent 30 consists of a length of wire, one end of which is gripped by the plate 2t) against one side wall of the box and the other end of which protrudes through a slot in the other side wall into engagement with the knob. The detent may cooperate with a stop 34 protruding from the knob.

In order to assist in threading up, that is to say, in placing the yarn (by means of a loading stick) over the surface of the downwardly inclined support 7 and beneath the feeler 12 upwards so that it then snaps and then moving .the support up to operative position, the mechanism is provided with a guard consisting of two wires 31 whichare attached to the base of the box 1, one at each side of the latter and curved upwards and outwards to terminate in substantially horizontal parts 32 that, when the support 7 is in operative position, lie slightly below the plane of the latter. These horizontal parts 32 terminate in up-turned ends joined by a crossbar 33 and vthe support is disposed between them. This cross-bar 33 limits upward movement of the support 7.

The guard 31 prevents the support from being pushed up to an undesirable extent by the loading stick.

It will be appreciated that while the yarn is running normally over the support 7 as shown in Fig. 1, small uctuations in yarn tension may cause the support and feeler to fall and rise slightly, but do not cause the mechanism to operate. If the tension drops to an undue extent or if the yarn breaks, the feeler 12 falls, the contacts 14, 15 close to complete a circuit, and this is utilised to bring the stop motion into operation. Before the mechanism can be threaded up again, it is necessary to swing the support down to or beyond its discharge position. For this purpose, one arm of the support may have a protrusion rearwards of its journal.

If the tension rises to an undue extent, the support 7 is pulled down, the feeler falls, contacts 14, 15 close, and the stop motion is brought into operation. Moreover, the support 7 snaps past its dead centre position so that the yarn can slide 0H it, beneath the ends 13 of the feeler; this provides a momentary surplus of yarn that can be consumed by the textile machine before the stop motion becomes fully effective, thus avoiding a yarn breakage and, in the case of a knitting machine, the possibility of a press-off or a partial press-oil.

What we claim is:

l. A yarn detecting mechanism for textile machine stop motions, comprising a holder, a support for supporting yarn against the tension thereof, a feeler to rest against a yarn on said support, means mounting the support on said holder for yielding movement in the event of undue increase in yarn tension, means mounting the feeler on said holder for tripping movement in the same direction as the yielding movement of the support upon absence of yarn and upon undue decrease in yarn tension and upon said yielding movement of the support, a snap action over centre device connected to the support to urge it to normal yarn supporting position and upon predetermined yielding movement of said support to move the support towards a yarn discharging position, and stop motion actuating means operable upon tripping movement of said feeler.

2. A yarn detecting mechanism for textile machine stop motions comprising a holder, a yarn support, means pivotally mounting said support on the holder, a feeler to engage a yarn extending across said support, means movably mounting said feeler on the holder for tripping movement on absence of or yielding movement of the yarn, a crank arm connected to said support, yieldable means acting on said crank arm as an over centre device so as normally to urge the support to a yarn supporting position but on predetermined movement of said support yby the yarn out of such position to snap over and urge the support still further from said position, and stop motion actuating means operable on tripping movement of said feeler.

3. A yarn detecting mechanism for textile machine stop motions for detecting absence of the yarn and undue increase and decrease in yarn tension, comprising `a holder, a yarn support having spaced yarn engaging members extending from the holder, means pivotally mounting said support on the holder for yielding movement upon undue increase in yarn tension, a'feeler of shorter length than said support adapted to rest against a yarn on said support between said spaced yarn engaging members, means pivotally mounting said feeler on the holder at a level below that of the pivotal axis of the support, yieldable means acting on said support to urge it over a dead centre position to normal yarn supporting position and stop motion actuating means operable by said feeler on release of the latter bythe yarn.

4. A yarn detecting mechanism for textile machine stop motions for detecting absence of the yarn and undue increase and decrease in yarn tension, comprising a holder, a yarn support having spaced yarn engaging members extending from the holder, means pivotally-mounting said support on the holder for yielding movement upon undue increase in yarn tension, a feeler of shorter length than said support adapted to rest against a yarn on said support between said spaced yarn engaging members, means pivotally mounting said feeler on the holder for tripping movement in the same direction as the movement of said support, a yieldable snap action over centre device connected to the support to urge it to normal yarn supporting position and also upon predetermined movement of said support to move the support towards a yarn discharging position, and stop motion actuating means operable upon tripping movement of said eeler.

5. A yarn detecting mechanism for textile machine stop motions for detecting absence of the yarn and undue increase and decrease in yarn tension, comprising holder, a yarn support having spaced yarn engaging members extending from the holder, means pivotally mounting said support on the holder for movement upon undue increase in yarn tension, a crank arm connected to said support, yieldable means acting on said crank arm as an over centre device so as normally to urge the support to a yarn supporting position but on predetermined movement of said support by the yarn out of such position to snap over and urge the support still further from said position, a feeler of a shorter length than said support adapted to rest against a yarn on said support between said spaced yarn engaging members, means pivotally mounting said feeler on the holder at a level beiow that on the pivotal axis of the support and stop motion actuating means adapted for operation of said feeler on release of the latter by the yarn.

6. A yarn detecting mechanism for textile machine stop motions, which comprises a holder, a yarn support pivoted to said holder and including a free end portion extending away from the holder adapted to support yam against its tension, said support being movable between a normal yarn supporting position and a yarn discharging position, said support also including a crank, resilient means connected at one end to said crank in otset relation to the pivotal axis of the support and at its other end to the holder, the direction of force exerted by said resilient means upon said crank when the support is in its normal position being closely adjacent a dead centre relationship but on that side thereof which urges the support in a direction against yarn tension, whereby when yarn tension increases detrimentally the crank will be swung over centre with relation to the resilient means so that the support will then be moved by the resilient means to its yarn discharging position, a feeler pivoted to said holder and including a free end portion interdigitated with said free end portion of the support such that yarn is disposed therebetween, said feeler being movable when unsupported by yarn to a yarn discharging position, stop means limiting the yarn discharging position of the feeler with relation to the yarn discharging position of the support so that when the same are in such positions` the free end portions thereof will be separated to permit yarn to be disengaged therefrom, and stop motion actuating means operable upon movement of the feeler to its yarn discharging position.

7. A yarn detecting mechanism for textile machine stop motions, comprising a holder, a support for supporting yarn against the tension thereof, a feeler to rest against a yarn on said support, said support and said feeler including interdigitated free end portions with the yarn disposed therebetween, means mounting the support on said holder for yielding movement in the event of undue increase in yarn tension, means mounting the teeler on said holder for tripping movement in the general direction as the yielding movement of the support upon absence of yarn and upon undue decrease in yarn tension and upon said yielding movement of the support,` a snap action over centre device connected to the support to urge it to its normal yarn supporting position and upon predetermined yielding movement of said support to move the support toward a yard discharging position, means limiting the tripped position of said feeler whereby when the teeler and support are in the yarn discharging position, the free end portions thereof will be separated to release the yarn, and stop motion actuating means operable upon tripping movement of said feeler.

References Cited in the tile of this patent UNlTED STATES PATENTS 1,778,097 Wachsman Oct. 14, 1930 

